JP2015120302A - Control apparatus of injection machine having function for reducing synchronization error - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the control apparatus of an injection machine having a function for reducing synchronization errors, capable of correcting the torque limiting value such that the synchronization of motors is satisfactorily maintained.SOLUTION: A control apparatus includes position control parts 51A and 51B for inputting positional commands, speed control parts 53A and 53B, torque limiting parts 54A and 54B, current control parts 56A and 56B, differential processing parts 57A and 57B, a correction amount calculation part 52, and a torque limiting value storage part 55. A synchronization error detection part 58 calculates and outputs the difference between a position feedback from the motor of a master shaft 60M and a position feedback from the motor of a slave shaft 60S as a synchronization error. A correction amount calculation part 52 calculates and outputs the correction amount of the torque command corresponding to the synchronization error inputted from the synchronization error detection part 58. In an adder 59, the correction value of the torque command outputted from the correction amount calculation part 52 and the torque limiting value stored in the torque limiting value storage part 55 are added and outputted to the torque limiting part 54B.

Description

  The present invention relates to an injection molding machine control device, and more particularly to an injection molding machine control device having a function of reducing synchronization errors.

  An injection molding machine using a servo motor as a shaft drive mechanism is known. In the case of a small injection molding machine, there are many cases where a single servo motor is provided for each driven member such as an injection part and a mold clamping part, and in the case of a large injection molding machine, a large shaft driving force is required. Since it is necessary, a technique for driving a single driven member by providing a plurality of servo motors is known. At this time, as a technique for maintaining position synchronization among a plurality of servo motors, for example, as described in Patent Document 1, a position deviation calculating means for calculating a position deviation amount between a plurality of driven parts is provided. There is known a technique for controlling each electric motor by correcting the control amount for each electric motor based on the positional deviation amount calculated by the positional deviation calculating means.

JP 2002-137269 A JP 2002-370270 A

  By the way, when driving the driven member of the injection molding machine, in order to prevent an excessive force from being applied to the driven member, a mold or a screw attached to the driven member, the torque of the servo motor is set to a predetermined torque or less. There may be restrictions. At this time, if the torque of multiple servo motors is limited to the same predetermined torque or less, the control amount to each motor is corrected based on the difference in position and speed between the multiple servo motors. Even then, since each motor is driven with the same predetermined torque, there is a possibility that the position synchronism between the plurality of servo motors may deteriorate.

  In Patent Document 2, when a single actuator is controlled by a plurality of servo motors, particularly by limiting the output torque of the servo motor, a difference in rotation angle between the servo motors is detected, and the difference becomes a predetermined value. There is known a technique for stopping the drive of a servo motor when it exceeds. However, in the technique described in Patent Document 2, when the position synchronism between a plurality of servo motors deteriorates, the servo motor drive is merely stopped, and the position synchronism deteriorates while limiting the torque of the servo motor. There was a problem that it was difficult to control so as not to.

  Accordingly, an object of the present invention is to limit the driving torque of each motor to each torque limit value or less and provide synchronism between the motors when providing a plurality of servo motors for driving one driven member. Another object of the present invention is to provide a control device for an injection molding machine having a function of reducing a synchronization error, wherein the torque limit value is corrected so as to be kept good.

The invention according to claim 1 of the present application is a control device for an injection molding machine that drives one driven member in an injection molding machine with a plurality of shafts, and a torque that limits a torque of the plurality of shafts that drive the driven members. Torque limit value correction that corrects the torque limit value of the torque limit unit so that the limit unit, the synchronization error detection unit that detects mutual synchronization errors of the plurality of axes, and the detected synchronization error of each axis become small A control device for an injection molding machine.
According to a second aspect of the present invention, the torque limit value correction unit sets torque limit values for all axes including the only master axis among the plurality of axes, or for other slave axes excluding the only master axis, respectively. The control apparatus for an injection molding machine according to claim 1, wherein correction is performed.
According to a third aspect of the present invention, the synchronization error detector is configured such that the difference between the position of the master axis and each of the other slave axes, the difference between the average position of all the axes and the position of each axis, or the corresponding axis for each axis. 3. The control of an injection molding machine according to claim 1, wherein a synchronization error is detected based on any one of a position and a difference between average positions of other axes. Device.
According to a fourth aspect of the present invention, the torque limit value correction unit corrects the torque limit value in the traveling direction to be larger for an axis that is delayed in movement with respect to the other axes among the plurality of axes. And correcting at least one of the plurality of axes that are moving with respect to the other axes so as to reduce the torque limit value in the traveling direction. It is a control apparatus of the injection molding machine as described in any one of Claims 1-3.

  According to the present invention, when a plurality of servo motors are provided and driven for one driven member, the driving torque of each motor is limited to each torque limit value or less, and the synchronism between the motors is kept good. In addition, an injection molding machine control device having a function of correcting the torque limit value can be provided.

It is a figure explaining embodiment which correct | amends the torque limit value of a slave axis | shaft. It is a figure explaining embodiment which correct | amends the torque limit value of both a master axis | shaft and a slave axis | shaft. It is a figure explaining embodiment in the case of driving with 3 axes to one driven member. It is a figure explaining embodiment which detects and correct | amends a synchronous error based on the difference of speed instead of the difference of a position. It is a figure explaining embodiment which shares a position control part with a some axis | shaft. It is a figure explaining embodiment which shares a position control part and a speed control part with a some axis | shaft.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. When the control device for an injection molding machine of the present invention is provided with a plurality of servo motors for driving one driven member, the drive torque of each motor is limited to a torque limit value or less and between the motors. The torque limit value is corrected so as to maintain good synchronization.

<Embodiment 1>
FIG. 1 is a diagram for explaining an embodiment for correcting a torque limit value of a slave shaft. The control device that controls the motor of the master shaft 60M and the motor of the slave shaft 60S includes position control units 51A and 51B that input position commands output from the host control unit, speed control units 53A and 53B, and a torque limiting unit. 54A, 54B, current control units 56A, 56B, differentiation processing units 57A, 57B, a correction amount calculation unit 52, and a torque limit value storage unit 55.

  The position controller 51A calculates and outputs a speed command corresponding to the position deviation based on the difference between the position command and the position feedback fed back from the motor of the master shaft 60M (target position-actual position). The position control unit 51B calculates and outputs a speed command corresponding to the position deviation based on the difference between the position command and the position feedback from the motor of the slave shaft 60S (target position-actual position). Note that the position detectors 61M and 61S are built in the motors of the respective axes, and position feedback is fed back from the position detectors.

  The speed control unit 53A calculates a torque command corresponding to the speed deviation based on the difference between the speed command output from the position control unit 51A and the speed feedback of the motor of the master shaft 60M fed back from the differentiation processing unit 57A. ,Output. The speed control unit 53B calculates a torque command corresponding to the speed deviation based on the difference between the speed command output from the position control unit 51B and the speed feedback of the motor of the slave shaft 60S fed back from the differentiation processing unit 57B. ,Output.

  The torque limiting unit 54A compares the torque command output from the speed control unit 53A with the torque limit value stored in the torque limit value storage unit 55. As a result of the comparison, the smaller absolute value is used as the torque command value. The current is output to the current control unit 56A. If the torque limit value stored in the torque limit value storage unit 55 is exceeded, the torque command input from the speed control unit 53A is limited. The torque limiting unit 54B compares the torque command output from the speed control unit 53B with the torque limit value output from the adder 59, and uses the smaller absolute value as the torque command value as a result of the comparison. To 56B.

  The current control unit 56A receives the torque command output from the torque limiting unit 54A, and supplies current to the motor of the master shaft 60M according to the input torque command. The current control unit 56B receives the torque command output from the torque limiting unit 54B, and supplies current to the motor of the slave shaft 60S according to the input torque command.

  The differentiation processing unit 57A differentiates the position feedback fed back from the motor of the master shaft 60M, and feeds it back to the speed control unit 53A as speed feedback. Further, the differential processing unit 57B performs differential processing on the position feedback fed back from the motor of the slave shaft 60S, and feeds it back to the speed control unit 53B as speed feedback.

  The synchronization error detector 58 calculates and outputs the difference between the position feedback fed back from the motor of the master shaft 60M and the position feedback fed back from the motor of the slave shaft 60S as a synchronization error. The synchronization error output from the synchronization error detection unit 58 is input to the correction amount calculation unit 52. The correction amount calculation unit 52 calculates the correction amount of the torque limit value corresponding to the synchronization error input from the synchronization error detection unit 58 and outputs it to the adder 59. In the adder 59, the correction amount of the torque limit value output from the correction amount calculation unit 52 and the torque limit value stored in the torque limit value storage unit 55 are added, and the torque limit unit 54B is used as the corrected torque limit value. Is output.

<Embodiment 2>
FIG. 2 is a diagram illustrating an embodiment in which the torque limit values of both the master axis and the slave axis are corrected. The control device that controls the motor of the master shaft 60M and the motor of the slave shaft 60S includes position control units 51A and 51B that input position commands output from the host control unit, speed control units 53A and 53B, and a torque limiting unit. 54A, 54B, current control units 56A, 56B, differentiation processing units 57A, 57B, a correction amount calculation unit 52, and a torque limit value storage unit 55.

  The position control unit 51A, the position control unit 51B, the speed control unit 53A, the speed control unit 53B, the current control unit 56A, the current control unit 56B, the differential processing unit 57A, and the differential processing unit 57B have the same configuration as that of the first embodiment. .

  The torque limiting unit 54A compares the torque command input from the speed control unit 53A with the torque limit value input from the subtractor 59A, and outputs the comparison result to the current control unit 56A as a torque command value. The torque limiter 54B compares the torque command input from the speed controller 53B with the torque limit value input from the adder 59, and outputs the comparison result to the current controller 56B as a torque command value.

  The synchronization error detector 58 calculates and outputs the difference between the position feedback fed back from the motor of the master shaft 60M and the position feedback fed back from the motor of the slave shaft 60S as a synchronization error. The synchronization error output from the synchronization error detection unit 58 is input to the correction amount calculation unit 52. The correction amount calculation unit 52 calculates the correction amount of the torque limit value corresponding to the synchronization error input from the synchronization error detection unit 58 and outputs it to the subtractor 59A and the adder 59. In the subtractor 59A, the correction amount of the torque limit value output from the correction amount calculation unit 52 is subtracted from the torque limit value stored in the torque limit value storage unit 55, and is output to the torque limit unit 54A. In the adder 59, the correction amount of the torque limit value output from the correction amount calculation unit 52 and the torque limit value stored in the torque limit value storage unit 55 are added and output to the torque limit unit 54B.

<Embodiment 3>
FIG. 3 is a diagram illustrating an embodiment in the case of three axes. The control device that controls the motor of the master shaft 60M, the motor of the slave shaft 60S1, and the motor of the slave shaft 60S2 includes position control units 51A, 51B, and 51C that input position commands output from the host control unit, and a speed control unit. 53A, 53B, 53C, torque limiting units 54A, 54B, 54C, current control units 56A, 56B, 56C, differentiation processing units 57A, 57B, 57C, correction amount calculating units 52A, 52B, and torque limit value storage Part 55.

  The position control unit 51A, the position control unit 51B, the speed control unit 53A, the speed control unit 53B, the current control unit 56A, the current control unit 56B, the differential processing unit 57A, and the differential processing unit 57B have the same configuration as that of the first embodiment. .

  The position control unit 51B that controls the slave shaft 60S1 has the same configuration as the position control unit 51B that controls the slave shaft 60S of the first embodiment. The position controller 51C calculates and outputs a speed command corresponding to the position deviation based on the difference between the position command and the position feedback fed back from the motor of the slave shaft 60S2 (target position-actual position). Note that the position detectors 61M, 61S1, and 61S2 are built in the motors of the respective axes, and position feedback is fed back from the position detectors.

  The speed controller 53B that controls the slave shaft 60S1 has the same configuration as the speed controller 53B that controls the slave shaft 60S of the first embodiment. The speed control unit 53C calculates a torque command corresponding to the speed deviation based on the difference between the speed command output from the position control unit 51C and the speed feedback of the motor of the slave shaft 60S2 fed back from the differentiation processing unit 57C. ,Output.

  The torque limiting unit 54A compares the torque command input from the speed control unit 53A with the torque limit value stored in the torque limit value storage unit 55, and outputs the comparison result to the current control unit 56A as a torque command value. . The torque limiter 54B compares the torque command input from the speed controller 53B with the torque limit value input from the adder 59, and outputs the comparison result to the current controller 56B as a torque command value. The torque limiting unit 54C compares the torque command output from the speed control unit 53C with the torque limit value input from the adder 59B, and outputs the comparison result to the current control unit 56C as a torque command value.

  The current control unit 56C receives the torque command output from the torque limiting unit 54C, and supplies current to the motor of the slave shaft 60S2 according to the input torque command.

  The differentiation processing unit 57C differentiates the position feedback fed back from the motor of the slave shaft 60S2, and feeds it back to the speed control unit 53C as speed feedback.

The synchronization error detector 58A calculates and outputs the difference between the position feedback fed back from the motor of the master shaft 60M and the position feedback fed back from the motor of the slave shaft 60S1 as a synchronization error with respect to the slave shaft 60S1. The synchronization error detector 58B calculates and outputs the difference between the position feedback fed back from the motor of the master shaft 60M and the position feedback fed back from the motor of the slave shaft 60S2 as a synchronization error with respect to the slave shaft 60S2.
The synchronization error output from the synchronization error detection unit 58A is input to the correction amount calculation unit 52A. The correction amount calculation unit 52A calculates the correction amount of the torque limit value corresponding to the synchronization error input from the synchronization error detection unit 58A, and outputs it to the adder 59. In the adder 59, the correction amount of the torque command output from the correction amount calculation unit 52A and the torque limit value stored in the torque limit value storage unit 55 are added and output to the torque limit unit 54B.

  The synchronization error output from the synchronization error detection unit 58B is input to the correction amount calculation unit 52B. The correction amount calculation unit 52B calculates the correction amount of the torque limit value corresponding to the synchronization error input from the synchronization error detection unit 58B, and outputs it to the adder 59B. The adder 59B adds the correction amount of the torque command output from the correction amount calculation unit 52B and the torque limit value stored in the torque limit value storage unit 55, and outputs the result to the torque limit unit 54C.

<Embodiment 4>
FIG. 4 is a diagram for explaining an embodiment for detecting and correcting a synchronization error based on a speed difference instead of a position difference. The control device that controls the motor of the master shaft 60M and the motor of the slave shaft 60S includes position control units 51A and 51B that input position commands output from the host control unit, speed control units 53A and 53B, and a torque limiting unit. 54A, 54B, current control units 56A, 56B, differentiation processing units 57A, 57B, a correction amount calculation unit 52C, and a torque limit value storage unit 55.

  Position control unit 51A, position control unit 51B, speed control unit 53A, speed control unit 53B, torque limiting unit 54A, torque limiting unit 54B, current control unit 56A, current control unit 56B, differentiation processing unit 57A, differentiation processing unit 57B The configuration is the same as that of the first embodiment.

  The synchronization error detector 58C performs speed feedback obtained by differentiating position feedback fed back from the motor of the master shaft 60M by the differentiation processor 57A and position feedback fed back from the motor of the slave shaft 60S. The difference from the speed feedback obtained by performing the differentiation process is calculated as a synchronization error and output. The synchronization error output from the synchronization error detection unit 58C is input to the correction amount calculation unit 52C. The correction amount calculation unit 52C calculates the correction amount of the torque limit value corresponding to the synchronization error input from the synchronization error detection unit 58C and outputs the correction amount to the adder 59. The adder 59 adds the correction amount of the torque limit value output from the correction amount calculation unit 52C and the torque limit value stored in the torque limit value storage unit 55, and outputs the sum to the torque limit unit 54B.

<Embodiment 5>
FIG. 5 is a diagram illustrating an embodiment in which the position control unit is shared by a plurality of axes. The control device that controls the motor of the master shaft 60M and the motor of the slave shaft 60S includes a position control unit 51 that inputs a position command output from the host control unit, speed control units 53A and 53B, a torque limiting unit 54A, 54B, current control units 56A and 56B, differential processing units 57A and 57B, a correction amount calculation unit 52, and a torque limit value storage unit 55.

  The position control unit 51 calculates and outputs a speed command corresponding to the position deviation based on the difference between the position command and the position feedback fed back from the motor of the master shaft 60M (target position-actual position). Note that the position detectors 61M and 61S are built in the motors of the respective axes, and position feedback is fed back from the position detectors.

  The speed control unit 53A calculates a torque command corresponding to the speed deviation based on the difference between the speed command output from the position control unit 51 and the speed feedback of the motor of the master shaft 60M fed back from the differentiation processing unit 57A. ,Output. The speed control unit 53B calculates a torque command corresponding to the speed deviation based on the difference between the speed command output from the position control unit 51 and the speed feedback of the motor of the slave shaft 60S fed back from the differentiation processing unit 57B. ,Output.

  The torque limiting unit 54A, the torque limiting unit 54B, the current control unit 56A, the current control unit 56B, the differentiation processing unit 57A, the differentiation processing unit 57B, and the synchronization error detection unit 58 have the same configuration as that of the first embodiment.

<Embodiment 6>
FIG. 6 is a diagram illustrating an embodiment in which a position control unit and a speed control unit are shared by a plurality of axes. The control device that controls the motor of the master shaft 60M and the motor of the slave shaft 60S includes a position control unit 51 that inputs a position command output from the host control unit, a speed control unit 53, and torque limiting units 54A and 54B. Current control units 56A and 56B, a differential processing unit 57, a correction amount calculation unit 52, and a torque limit value storage unit 55.

  The position control unit 51 calculates and outputs a speed command corresponding to the position deviation based on the difference between the position command and the position feedback fed back from the motor of the master shaft 60M (target position-actual position). Note that the position detectors 61M and 61S are built in the motors of the respective axes, and position feedback is fed back from the position detectors.

  The speed control unit 53 calculates a torque command corresponding to the speed deviation based on the difference between the speed command output from the position control unit 51 and the speed feedback of the motor of the master shaft 60M fed back from the differentiation processing unit 57A. Output.

  The torque limiting unit 54A compares the torque command input from the speed control unit 53 with the torque limit value stored in the torque limit value storage unit 55, and outputs the comparison result to the current control unit 56A as a torque command value. . The torque limiting unit 54B compares the torque command input from the speed control unit 53 with the torque limit value output from the adder 59, and outputs the comparison result to the current control unit 56B as a torque command value.

  The current control unit 56A, the current control unit 56B, the differentiation processing unit 57A, the differentiation processing unit 57B, and the synchronization error detection unit 58 have the same configuration as that of the first embodiment.

Here, the torque limiting unit described above will be described.
The torque limiting unit limits a torque command value commanded from a higher-level control unit such as a speed control unit to a torque limit value or less, and then commands a lower-level control unit such as a current control unit. The torque limit value sets an appropriate torque value for protecting the driven member, a mold or a screw attached to the driven member. The calculation is performed with correction so as to keep the synchronism between the motors good.

  For example, a case where a driven member is driven by two axes of a master axis and a slave axis will be described. If the friction resistance during operation of the slave axis is greater than that of the master axis, when the master and slave axes are driven with the same torque limit value, the slave axis movement is delayed from the master axis (that is, the position of the slave axis is 2), or the slave axis speed is lower than that of the master axis), and the synchronicity between the two axes deteriorates. Therefore, by performing proportional-integral calculation on the position difference or speed difference (synchronization error) between the two axes and correcting the torque limit value using the output value as the correction value, the torque limit value of each axis is Correction is made to reduce the synchronization error, and the synchronization between the two axes can be kept good.

  At this time, the torque limit value of one (master axis) may not be corrected, but only the torque limit value of the other (slave axis) may be corrected (see FIG. 1), or the master and slave axes. It is also possible to correct each of the torque limit values of the master and slave shafts by adding a correction value having the opposite sign to each of the torque limit values (see FIG. 2). For example, when the movement of the slave axis is delayed from the master axis, correction may be made to increase the torque limit value in the traveling direction of the slave axis so that the slave axis advances, or the torque limit value of the slave axis A correction may be made so that the torque limit value with respect to the traveling direction of the master axis is reduced so that the master axis is delayed while the master axis is delayed.

Next, the synchronization error detection unit will be described.
The synchronization error detection unit may detect the synchronization error based on the difference between the master axis position and the slave axis position (see FIGS. 1, 2, and 3), or the master axis speed and the slave axis. The synchronization error may be detected based on the difference in speed (see FIG. 4). Further, the synchronization error may be detected based on the difference in position deviation between the master axis and the slave axis (the deviation between the command position and the actual position) instead of the position.

  Further, when there are three or more axes for driving the driven member, the average position of all the axes is obtained, and the respective synchronization errors are detected based on the difference between the average position and the position of each axis. Alternatively, for each axis, the synchronization error of each axis may be detected based on the difference between the position of the corresponding axis and the average position of the other axes, or a single master axis and a plurality of slave axes may be detected. The synchronization error of each slave axis may be detected based on the difference between the position and speed of the master axis and each slave axis.

  The position and speed of each axis may be detected by providing a rotary encoder in the motor, or by detecting a position / speed detector in the driven member.

  In the above description, the case where the torque command value is limited to the torque limit value or less has been described. However, in the case of a servo motor, the torque command value and the current command value substantially match, so that the current command value is limited to the current limit value or less. Even if configured, the same effect can be obtained. Therefore, the current command value may be limited to the current limit value or less, and the current limit value may be corrected so as to reduce the synchronization error.

  In addition, the present invention can be used in a control configuration (FIG. 1) having a position control unit, a speed control unit, and a torque limiting unit for each of a plurality of axes. It can be used in a control configuration (FIG. 5) having a speed control unit and a torque limiting unit for each axis, and the position control unit and the speed control unit are shared by a plurality of axes, and each of the plurality of axes has a torque limiting unit. It can also be used in the control configuration (FIG. 6).

  As described above, according to the present invention, when a plurality of servo motors are provided and driven for one driven member, the driving torque of each motor is limited to each torque limit value or less, and between the motors. It is possible to provide a control device for an injection molding machine having a function of correcting the torque limit value so as to maintain good synchrony.

51, 51A, 51B, 51C Position control unit 52, 52A, 52B Correction amount calculation unit 53A, 53B, 53C Speed control unit 54A, 54B, 54C Torque limiting unit 55 Torque limit value storage unit 56A, 56B, 56C Current control unit 57A , 57B, 57C Differential processing unit 58, 58A, 58B Synchronization error detection unit 58C Synchronization error detection unit 59, 59B Adder 59A Subtractor 60M Master axis 60S Slave axis 60S1 First slave axis 60S2 Second slave axis

Claims (4)

In an injection molding machine control device for driving one driven member in an injection molding machine with a plurality of axes,
A torque limiting unit that limits torque of a plurality of shafts that drive the driven member;
A synchronization error detection unit for detecting mutual synchronization errors of the plurality of axes;
A torque limit value correction unit that corrects the torque limit value of the torque limit unit so that the detected synchronization error of each axis becomes small;
An injection molding machine control device comprising:   The torque limit value correcting unit corrects torque limit values for all axes including the only master axis among the plurality of axes, or for other slave axes excluding the only master axis, respectively. Item 2. A control device for an injection molding machine according to Item 1.   The synchronization error detection unit is the difference between the position of the master axis and each of the other slave axes, or the difference between the average position of all the axes and the position of each axis, or the average of the position of the corresponding axis and the other axes for each axis. The control apparatus for an injection molding machine according to claim 1, wherein a synchronization error is detected based on any one of the position differences.   The torque limit value correction unit corrects the torque limit value with respect to the traveling direction to be increased with respect to an axis whose movement is delayed with respect to the other axes among the plurality of axes; and 4. The shaft according to claim 1, wherein at least one of the shafts that are moving relative to the other shafts is corrected so as to reduce the torque limit value in the traveling direction. The control apparatus of the injection molding machine as described in any one.